An iron runner having a wear lining which during operation actually contacts the iron and a permanent lining in which the wear lining is contained is known, and may be air-cooled either by forced or ambient air or be water-cooled or cooled in other ways, for example with a glycol/water mixture.
The wear lining of an iron runner may consist of a refractory concrete, and the permanent lining may be carbon in combination with aluminium oxide bricks, or just aluminium oxide bricks. It is usual for the outside of the iron runner to be formed by a steel outer casing, sometimes known as a box. For strength considerations this steel may not receive any temperatures higher than approx. 260.degree. C. The crude iron comes out of the blast furnace directly into contact with the wear lining and has a temperature of approx. 1500.degree. C.-1550.degree. C. As a result substantial thermal stresses occur in the structure of the iron runner, expanding it considerably.
A typical iron runner may be twenty meters long and three meters wide. Through contact with the crude iron the wear lining of a refractory concrete expands longitudinally about 18 centimeters and in width about 2.7 centimeters.
However, the permanent lining, outside the wear lining, is subjected to a lower temperature and moreover is made of another material so that it expands much less. As a consequence of the stresses in the wear lining and the permanent lining resulting from these differences, these linings tend to crack, especially near the bottom of the runner. Also, given that the iron runner is anchored at the furnace end to prevent it from moving there, and the bottom of the runner does expand horizontally, this cracking occurs mainly in the side walls of the linings.
The first mentioned cracking arising from temperature difference occurs even if the linings are provided with expansion joints for taking up the expansion caused by going from the cold condition to the operational condition. This is because these linings do not experience uniform expansion.
Cracking also leads to the problem that, when the iron runner is taken out of service for maintenance, iron solidifies in the cracks. Once the iron runner is put into operation again, further expansion then takes place so that the dimensions of the iron runner increase still further. Significant distortions then occur whereby the iron runner structure undergoes further damage. During operation the cracking leads to the risk of the molten material breaking-through, necessitating costly repair work to the entire iron runner structure.
The invention relates to a method and structure for handling molten material wherein the linings are subjected to substantial compression both before and during their operation.
In the prior art, GB-A-773272 shows compression springs acting from side walls of a steel casing on an end plate of the casing of a transfer trough so as to compensate for the thermal expansion of that casing in the longitudinal direction being greater than that of the refractory mass. The end plate is movable relative to the side walls of the casing.
"Iron and Steel Engineer" October 1988 pages 35-37 and 47-51 shows various methods of cooling troughs or runners and discusses various conformations of working and permanent linings, some of which are made of individual bricks. On page 48 FIG. 2 shows a structure, said to be patented, which includes lining layers of high thermal conductivity.
AT-B-379172 shows a slag runner of which an inner boundary between coolant medium and the slag is laterally flexed by a hydraulic or pneumatic cylinder and piston arrangement.